Molecular-beam epitaxy synthesis and ARPES studies of SrMoO3 thin films with record low resistivities*

Although isostructural to their ruthenate counterparts (SrRuO₃ and unconventional superconductor Sr₂RuO₄), SrMoO₃ and Sr₂MoO₄ differ electronically as their 4d t_2g orbitals are occupied by two fewer electrons. The electronic transport properties of these systems are also markedly different. For instance, SrMoO₃ is the most conductive oxide perovskite, with a room temperature resistivity a factor of 40 lower than that of SrRuO₃. However, while the oxide molybdates offer an exciting platform for comparison to the ruthenates and for gaining insight into the influence of the Hund’s interactions and van Hove singularities in 4d oxides, challenges in synthesizing molybdates have left many questions unanswered.

Here we demonstrate the synthesis of thin film SrMoO₃ on TbScO₃ (110) substrates via molecular-beam epitaxy using a MoO₃ source. The room temperature resistivities of our films are ~17 uOhm-cm, which are lower than those reported for all other SrMoO₃ thin films. Furthermore, the residual resistivity ratios (R_300K /R_4K) of our films are greater than 20, better than those in the best bulk single crystals of SrMoO₃. With these much-improved samples, we characterize the quasiparticle band structure and self-energy of SrMoO3 films via angle-resolved photoemission spectroscopy (ARPES). We analyze the quasiparticle self-energy as a function of energy, momentum, and temperature, and investigate the band folding induced by the octahedral rotations as a function of temperature.